1. Field of the Invention
The present invention relates to a refrigerant composition and a refrigerating apparatus, and more particularly to a refrigerant composition which does not destroy the ozone layer, is nonflammable, is compatible well with refrigerating machine oil such as mineral oil and alkyl benzene, and presents a stable and uniform liquid phase, and to a refrigerating apparatus using the same.
2. Background Art
The conventional refrigerant hitherto used in the refrigerating machine is mostly dichlorodifluoromethane (hereinafter called R-12), or R-500 composed of an azeotropic mixture refrigerant of R-12 and 1,1-difluoroethane (hereinafter called r-152a). The boiling point of R-12 is xe2x88x9229.65xc2x0 C. at atmospheric pressure, and that of R-500 is xe2x88x9233.45xc2x0 C., which are ideal for ordinary conventional refrigerating apparatuses. Even when a suction temperature into a compressor is relatively high, they have properties of not raising the discharge temperature so high as to induce oil sludge of the compressor. Moreover, R-12 is compatible well with the refrigerating machine oil such as mineral oil of the compressor, and plays a role of returning the oil in the refrigerant circuit into the compressor.
These refrigerants, however, have a high latency of ozone destruction, and when released into the atmosphere to reach the ozone layer high above the earth, they destroy the ozone layer. The ozone layer destruction is induced by chlorine radical (Cl) in the constructions of the refrigerants. Accordingly, refrigerants not containing chlorine radical are expected as substitute refrigerants, such as difluoromethane (hereinafter called R-32), pentafluoroethane (hereinafter called R-125), and 1,1,1,2-tetrafluoroethane (hereinafter called R-134a). The boiling point of R-32 is xe2x88x9251.7xc2x0 C. at atmospheric temperature, that of R-125 is xe2x88x9248.5xc2x0 C., and that of R-134a is xe2x88x9226.0xc2x0 C.
These chlorine radical-free refrigerants R-32, R-125 and R-134a are poor in compatibility with general refrigerating machine oil such as mineral oil or alkyl benzene, and often caused lubrication troubles of the compressor due to worsening of returning of oil to the compressor, or sucking refrigerants separated from oil upon starting after shutdown, etc.
Accordingly, the present inventor attempted to mix these refrigerants which are poor in compatibility with mineral oil or alkyl benzene with n-pentane excellent in compatibility with them, and discovered that the refrigerating machine oil such as mineral oil and alkyl benzene discharged from the compressor into the refrigerant circuit can be recovered into the compressor even when using these refrigerant mixture.
The invention is hence intended to solve the above problems by presenting a refrigerant composition with a purpose of using refrigerating machine oil such as mineral oil and alkyl benzene in a refrigerant not containing chlorine radical, by blending a chlorine radical-free refrigerant with n-pentane having a boiling point of +36.07xc2x0 C. at atmospheric pressure, and a refrigerating apparatus using the same.
On the other hand, when the a chlorine radical-free refrigerant and n-pentane are separately supplied in refrigerating circuits, it is very difficult to feed them uniformly into the refrigerating circuits because of difference in vapor pressure between the two having difference in boiling point. Furthermore since the mixture of the two is not a uniform liquid phase, oil return to the compressor may be not sufficient. In addition, there is risk of fire induced if such refrigerant composition leaks. Accordingly, it is other object of the present invention to solve such problems by mixing such chlorine radical-free refrigerant and n-pentane preliminarily, and using them as a refrigerant composition having a stable and uniform liquid phase.
As a result of intensive study on the above subjects, the inventor has discovered that a nonflammable refrigerant composition having a stable and uniform liquid phase can be obtained by mixing a refrigerant poor in compatibility with mineral oil or alkyl benzene preliminarily with a specified amount of n-pentane having a boiling point of +36.07xc2x0 C. at atmospheric pressure excellent in compatibility with mineral oil or alkyl benzene, and that the refrigerating machine oil such as mineral oil and alkyl benzene discharged from the compressor into the refrigerant circuit can be recovered into the compressor even when such refrigerant composition is employed, thereby solving the above problems, and hence completed the invention.
The feature of the present invention relates to a refrigerant composition comprising difluoromethane, pentafluoroethane, 1,1,1,2-tetrafluoroethane, and n-pentane.
Furthermore, another feature of the present invention relates to a refrigerant composition prepared by mixing n-pentane preliminarily with 1,1,1,2-tetrafluoroethane, and mixing the mixture into a refrigerant of difluoromethane and pentafluoroethane, wherein the contained n-pentane is in a range of 0.1 wt. % to 14 wt. % of the total weight.
In addition, the third feature of the present invention relates to a refrigerant composition containing n-pentane by 14 wt. % or more in the preliminary mixture with 1,1,1,2-tetrafluoroethane, and by 14 wt. % or less in the finally resulted refrigerant.
The fourth feature of the present invention relates to a refrigerant composition composed of 1,1,1,2-tetrafluoroethane and n-pentane, wherein n-pentane is dissolved in 1,1,1,2-tetrafluoroethane in a range of 0.1 wt. % to 7.3 wt. % of total weight.
The fifth feature of the present invention relates to a refrigerating apparatus comprising a condenser for condensing and liquefying a refrigerant, an evaporator for evaporating a liquefied refrigerant, and a compressor for compressing an evaporated and vaporized refrigerant and discharging it into the condenser, wherein a refrigerant composition is used as the refrigerant to be compressed by the compressor.
The sixth feature of the present invention relates to a refrigerating apparatus wherein a refrigerant composition having n-pentane dissolved in 1,1,1,2-tetrafluoroethane by about 6 wt. % of the total weight.
Furthermore, the seventh feature of the present invention relates to a refrigerating apparatus wherein mineral oil or alkyl benzene oil is used as refrigerating machine oil.
The eighth feature of the present invention relates to a refrigerating apparatus wherein a rotary compressor is used as the compressor and alkyl benzene oil is used as refrigerating machine oil.
As the present invention is thus constituted, by mixing n-pentane excellent in compatibility with refrigerating machine oil such as mineral oil and alkyl benzene with a chlorine radical-free refrigerant poor in compatibility with refrigerating machine oil such as mineral oil and alkyl benzene, the refrigerating machine oil such as mineral oil and alkyl benzene discharged from the compressor into the refrigerant circuit can be recovered in the compressor.
In the present invention, moreover, n-pentane which is flammable and is hardly miscible with refrigerant such as R-32 and R-125 at ordinary temperature is preliminarily mixed in refrigerant R-134a at a predetermined rate, and is further mixed with refrigerants R-32 and R-125, and even when the mixing rate of n-pentane with refrigerants R-32 and R-125 varies, the mixing ratio of n-pentane is limited within 14 wt. %, and thereby n-pentane is not separated from R-32 and R-125 at ordinary temperature.
The refrigerant composition in which n-pentane is dissolved in R-134a in a range of 0.1 wt. % to 7.3 wt. % of the total weight is a nonflammable refrigerant composition with a stable and uniform liquid phase, not becoming uneven in the concentration distribution, or separating into two phases even if stored for a long period. Accordingly, the refrigerant composition of the present invention can be supplied precisely and stably into a refrigerating circuit, and is moreover compatible well with refrigerating machine oil, and therefore the refrigerating machine oil such as mineral oil and alkyl benzene discharged from the compressor into the refrigerant circuit can be easily recovered in the compressor. In addition, in case the refrigerant composition would leak, it involves no possibility of fire.
Furthermore, in the refrigerating apparatus according to the present invention comprising a condenser for condensing and liquefying a refrigerant, an evaporator for evaporating a liquefied refrigerant, and a compressor for compressing an evaporated and vaporized refrigerant and discharging into the condenser, by using any one of the refrigerant compositions above mixing n-pentane with an excellent compatibility with refrigerating machine oil such as mineral oil and alkyl benzene in a chlorine radical-free refrigerant, as the refrigerant to be compressed by the compressor, the refrigerating machine oil such as mineral oil and alkyl benzene discharged from the compressor into the refrigerant circuit can be easily recovered in the compressor.
The nonflammable refrigerant composition composed of chlorine radical-free refrigerant and n-pentane blended at a specific rate according to the present invention can be charged into a same gas cylinder, and therefore the nonflammable refrigerant composition can be precisely and stably supplied into the refrigerating circuit by a charging device coupled to the refrigerating circuit.
The combination of the type of compressor such as rotary compressor or reciprocating compressor and the type of refrigerating machine oil such as mineral oil or alkyl benzene is not particularly limited in the present invention. However, when the rotary compressor is used as the compressor, partly because return of oil into the compressor is smooth, it is desired to use an alkyl benzene oil as refrigerating machine oil.